This invention relates to image receptor media for thermal or piezo inkjet printing wherein the media comprises a hot melt material.
Image graphics are omnipresent in modem life. Images and data that warn, educate, entertain, advertise, etc. are applied on a variety of interior and exterior, vertical and horizontal surfaces. Nonlimiting examples of image graphics range from advertisements on walls or sides of trucks, posters that advertise the arrival of a new movie, warning signs near the edges of stairways.
The use of thermal and piezo inkjet inks have greatly increased in recent years with accelerated development of inexpensive and efficient inkjet printers, ink delivery systems, and the like.
Thermal inkjet hardware is commercially available from a number of multinational companies, including without limitation, Hewlett-Packard Corporation of Palo Alto, Calif., USA; Encad Corporation of San Diego, Calif., USA; Xerox Corporation of Rochester, N.Y., USA; LaserMaster Corporation of Eden Prairie, Minn., USA; and Mimaki Engineering Co., Ltd. of Tokyo, Japan. The number and variety of printers changes rapidly as printer makers are constantly improving their products for consumers. Printers are made both in desk-top size and wide format size depending on the size of the finished image graphic desired. Nonlimiting examples of popular commercial scale thermal inkjet printers are Encad""s NovaJet Pro printers and H-P""s 650C, 750C, and 2500CP printers. Nonlimiting examples of popular wide format thermal inkjet printers include H-P""s DesignJet printers, where the 2500CP is preferred because it has 600xc3x97600 dots/inch (dpi) resolution with a drop size in the vicinity of about 40 picoliters.
3M markets Graphic Maker Inkjet software useful in converting digital images from the Internet, ClipArt, or Digital Camera sources into signals to thermal inkjet printers to print such image graphics.
Inkjet inks are also commercially available from a number of multinational companies, particularly 3M which markets its Series 8551; 8552; 8553; and 8554 pigmented inkjet inks. The use of four principal colors: cyan, magenta, yellow, and black (generally abbreviated xe2x80x9cCMYKxe2x80x9d) permit the formation of as many as 256 colors or more in the digital image.
Media for inkjet printers are also undergoing accelerated development. Because inkjet imaging techniques have become vastly popular in commercial and consumer applications, the ability to use a personal computer to digitally print a color image on paper or other receptor media has extended from dye-based inks to pigment-based inks. And the media must accommodate that change. Pigment-based inks provide more durable images because pigment particles are contained in a dispersion before being dispensed using a thermal inkjet print head.
Inkjet printers have come into general use for wide-format electronic printing for applications such as, engineering and architectural drawings. Because of the simplicity of operation and economy of inkjet printers, this image process holds a superior growth potential promise for the printing industry to produce wide format, image on demand, presentation quality graphics.
Therefore, the components of an inkjet system used for making graphics can be grouped into three major categories:
1 Computer, software, printer.
2 Ink.
3 Receptor medium.
The computer, software, and printer will control the size, number and placement of the ink drops and will transport the receptor medium through the printer. The ink will contain the colorant which forms the image and carrier for that colorant. The receptor medium provides the repository which accepts and holds the ink. The quality of the inkjet image is a function of the total system. However, the composition and interaction between the ink and receptor medium is most important in an inkjet system.
Image quality is what the viewing public and paying customers will want and demand to see. From the producer of the image graphic, many other obscure demands are also placed on the inkjet media/ink system from the print shop. Also, exposure to the environment can place additional demands on the media and ink (depending on the application of the graphic). Most common, durability of the image graphic is required in humid indoor or outdoor environments, especially locations capable of being soaked with rain or melting snow or ice.
Current inkjet receptor media are direct coated with a dual layer receptor medium according to the disclosure contained in U.S. Pat. No. 5,747,148 (Warner et al.) and are marketed by 3M under the brands 3M(trademark) Scotchcal(trademark) Opaque Imaging Media 3657-10 and 3M(trademark) Scotchcal(trademark) Translucent Imaging Media 3637-20. Other products marketed by 3M include Nos. 8522CP and 8544CP Imaging Media, the former having a coating on the imaging surface for controlling dot gain and the latter having a pigment management system and a fluid management system in pores of the membrane. With the rapid rise in usage of inkjet printing systems to create wide format graphics having digitally-produced images thereon, more and better inkjet receptor media are needed, especially those which rise to the level of precision and lighting requirements that are used for photographically-created image graphics.
These media have coatings provided by water-borne systems, either for entirely water-soluble or water-dispersible ingredients. Water-soluble ingredients are susceptible to loss of durability of the image graphic when encountering humid or wet environments. Most often, the image is created by printing of a water-based ink needs to be fixed to prevent ink migration and loss of precision of the image graphic. Water-dispersible ingredients are particularly difficult to handle during manufacturing to provide reproducible image receptive layers on substrates; working with emulsion-based delivery of coatings introduces a number of additional manufacturing factors that can affect efficiency and productivity.
An image receptor medium, comprising a base medium having a hot melt layer on one major surface. The hot melt layer has a melting temperature between 40 and 150xc2x0 C. An imaging layer lies atop the hot melt layer, wherein the imaging layer comprises a water-insoluble porous coating adapted to imbibe ink.
A method of preparing an imaging layer is also provided, a) applying a hot-melt layer to a base medium on one major surface thereon, b) applying a coating formulation to said hot-melt layer; and c) evaporating solvent to form the imaging layer.
A method of fixing an image graphic is also provided, which comprises providing the image receptor medium as described above, imparting an image to the medium by printing with an inkjet ink. Heat and pressure are then applied to the imaged graphic, thereby filling a substantial portion of pores in said porous coating with hot melt material.